I was driving on Interstate 355 South when I saw a huge lit up object in the sky 4 miles away. When I got closer to it I could see that it was too close to the ground and too big to be an airplane and I thought that maybe it was a blimp, but it looked too big to be a blimp. Also I saw huge white lights on it that where in the shape of rectangular windows and I saw a blue flashing light underneath the object. The object was flying west. I was near a tollbooth when I saw the object and by the time I got to the tollbooth the object was moving slowly west away from I355.